What is the best treatment for cellulitis?

Treatment of Cellulitis

For uncomplicated cellulitis, a 5-day course of an antibiotic active against streptococci is the recommended first-line treatment, with extension if the infection has not improved within this period. 1, 2

Antibiotic Selection Algorithm

Mild Cellulitis (Outpatient)

• First-line therapy:
  • Cephalexin 500 mg orally 3-4 times daily for 5-6 days 2
  • Alternative for penicillin-allergic patients: Clindamycin 300-450 mg orally three times daily for 5-6 days 2, 3

Moderate Cellulitis with Systemic Signs

• First-line therapy:
  • Consider coverage for both streptococci and MSSA
  • Amoxicillin-clavulanate 875/125 mg twice daily orally for 5-6 days 2
  • Alternative: Cefazolin 1 g every 8 hours IV 1

Severe Cellulitis (Hospitalization Required)

• First-line therapy:
  • Vancomycin plus either piperacillin-tazobactam or imipenem/meropenem for severe infections 1
  • Consider MRSA coverage if risk factors present (penetrating trauma, prior MRSA infection, nasal colonization with MRSA, injection drug use, or SIRS) 1, 2

MRSA Risk Assessment

• Add MRSA coverage if any of the following are present:
  • Penetrating trauma
  • Evidence of MRSA infection elsewhere
  • Nasal colonization with MRSA
  • Injection drug use
  • Systemic inflammatory response syndrome (SIRS)
  • High-risk populations: athletes, children, men who have sex with men, prisoners, military recruits, residents of long-term care facilities 1, 4

Duration of Treatment

• Standard duration: 5 days 1, 2
• Extend treatment if infection has not improved within 5 days 1
• Most patients should see improvement within 48-72 hours of appropriate antibiotic therapy 2

Adjunctive Measures

• Elevate affected area to reduce edema 1, 2
• Treat predisposing factors such as edema, obesity, eczema, venous insufficiency 1
• For lower-extremity cellulitis, examine interdigital toe spaces and treat fissuring, scaling, or maceration 1
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adult patients 1

Hospitalization Criteria

Hospitalize patients with:

• SIRS (fever, tachycardia, tachypnea, leukocytosis)
• Altered mental status
• Hemodynamic instability
• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Severe immunocompromise
• Failure of outpatient treatment 1, 2

Monitoring and Follow-up

• Monitor daily for first 48-72 hours to ensure response to antibiotics 2
• Seek immediate care if experiencing increasing pain, fever, extension of erythema, or development of bullae/skin sloughing 2
• Visible improvement in local signs and absence of signs of deeper infection indicate safe discharge 2

Prevention of Recurrence

• For patients with 3-4 episodes per year despite treatment of predisposing factors, consider prophylactic antibiotics:
  • Oral penicillin or erythromycin twice daily for 4-52 weeks, or
  • Intramuscular benzathine penicillin every 2-4 weeks 1
• Maintain good skin hygiene and promptly treat minor skin breaks 2
• Daily change of socks and careful drying between toes after showers 2

Common Pitfalls to Avoid

1. Misdiagnosis: Cellulitis has many mimics and is diagnosed clinically without a gold standard test 5
2. Overuse of broad-spectrum antibiotics: Reserve MRSA coverage for specific risk factors 1, 4
3. Inadequate duration: Ensure full 5-day course with extension if needed 1
4. Failure to address predisposing factors: Treating underlying conditions is crucial for preventing recurrence 1, 2
5. Unnecessary hospitalization: Most mild cases can be managed as outpatients 1